Aluminum alloys



Patented Oct. 31, 1933 UNITED STATES PATENT OFFICE Aluminum Company ofAmerica, Pittsburgh, Pa., a corporation of Pennsylvania No Drawing.Original application September 21,

1932, Serial No. 634,155.

plication November 645,118

Divided and this ap- 30, -1932. Serial No.

- 1 Claim. (01. 75-1) This invention relates to aluminum base alloyscontaining magnesium. The invention has for its object .the improvementof alloys of this class.

by the addition thereto of about 0.05 to 2.0 per 5 cent by weight ofcalcium. The invention is particularly concerned with the specificalloys hereinafter described. I

The claim of this application covers certain matter divided from mycopending application ,10- Serial No. 634,155 which is, in part, acontinuasubstantial amounts of magnesium. This did!- culty isencountered both in the making of sand castings and permanent mold orchill-mold castings, although the nature of the difllculty diflerssomewhat in each case. In the case of sand castings there occurs areaction between the molten aluminum base alloy containing magnesium andthe ordinary sand-mold materials, or vapors generated therefrom. Thereis also a reaction with the atmosphere. In -addition, themagnesium-containing aluminum base alloy does not flow freely throughnarrow mold sections at ordinary pouring temperatures and, if thepouring temperature be raised, the solidified alloy is unsound. If thealuminum base alloy contain- 5 ing magnesium be cast in a chill-mold thereaction eifect is minimized to some extent, but the troubles arisingfrom cold-shuts and mis-runs are accentuated because of the more rapidchilling .of the molten metal. The considerations 4o apply to thealuminum base alloys specifically disclosed herein and. particularly tosuch alloys I have discovered that when calcium is added to aluminumbase alloys of the type and composition herein described, thesedifliculties are, to a considerable extent, eliminated. The calciumshould .be present in amounts ranging from 0.05 per cent to 2.0 per centby weight subject to. specific considerations as hereinafter disclosed.

In the melting of aluminum alloys of the com-- positions hereindescribed, a viscous scum often forms at the surface of the moltenmetal. Failure oi the molten metal to run properly through narrow moldapertures is caused, in part, by

\ shreds or particles of this scum being suspended in the molten metaland offering a resistance to the free passage )f the. metal through theapertures. Regardless of the cause of this low fluidity, I havediscovered that the addition to the alloy of relatively small amounts ofcalcium. in the preferred range between 0.05 to 0.5 per cent, improvesthe casting characteristics to a very considerable extent andsimultaneously effects a reduction of the scum or dross collecting at ornear the surface. In the casting of articles in sand molds, I prefer toadd calcium in 5 amounts less than about 0.5 per cent except ininstances where some reduction of tensile strength or other mechanicalor tensile property is immaterial. In amounts of more than 0.5 per centthe calcium addition produces the advan- 7 tages enumerated herein buthas a tendency to lower some of the physical properties of the alloys.This effect is not harmful when calcium is present in amounts of about0.5 per cent or less, but when high strength is not a desideratum thecalcium may be used in amounts up to about 2.0 percent. In intricatepermanent mold castings, where casting troubles are very serious if nocalcium be, added, the improved physical properties obtained coincidentwith the produc- 3 tion of good castings more than offset the diminutionin properties which might otherwise result from the use of the calcium.

I have also discovered that when calcium is added to aluminum basealloys containing mag- 5 nesium, the amount of gas evolved duringsolidification of the alloys is considerably reduced. When from about0.05 per cent to 2.0 per cent by weight of calcium is added to thealloys, the amount of gas evolved becomes less marked with increasingcalcium content and the reductiorf of gas evolution may be so markedthat the molten metal c'ools to the solidification temperature with asmooth mirror-like surface. I

prefer to restrict the amount of calcium added 5 to 2.0 per cent or lesssince above this amount the physical properties of the alloys may be tooseriously aiiected. If the best physical properties are desired with animproved, although not complete,-degree of gas prevention, I keep thecalcium content of the alloys between 0.05 per cent and about 0.5 percent.

In the application of the principles of my invention I have determinedthat certain aluminum base alloys containing magnesium are particularlybenefited thereby. For example, a very useful aluminum base alloy is onecontaining about 2.0 to 9.0 per cent of magnesium and 0.05 per cent to2.0 per cent of calcium, as is also aluminum base alloy containing about2.0 to 11 15.0 per cent of magnesium, 0.1 to 3.5 per cent of cobalt, and0.05 to 2.0 per cent of calcium to which other elements such as copper,antimony, bismuth, nickel, manganese, and other well known alloyingelements may be added to produce particular properties therein.

Likewise is the addition of 0.05 to 2.0 per cent of calcium beneficialto thosealuminum base alloys which contain about 2.0 to 15.0 per cent ofmagnesium and 0.05 to 0.4 per cent of at least one of the class ofmetals here defined as antimony and bismuth, such alloys being veryuseful where use at high temperatures is contemplated. Calcium maylikewise be added to improve such alloys when they contain, in additionto magnesium and antimony and/or bismuth, one or more of such alloyingelements as cobalt, copper, nickel, manganese, zinc, etc., which may beadded to modify or produce a specific property in the alloy.

The addition of 0.05 to 2.0 per cent of calcium is very beneficial inthe case of a series of aluminum base alloys which contain as majoralloying elements about 2.0 to 10.0 per cent of magnesium and about 0.2to 5.0 per cent of nickel. For instance, an aluminum base alloycontaining 3.0 to 7.5 per cent of magnesium and 0.2 to 2.0 per cent ofnickel is improved by the addition of 0.05 to 2.0 per cent of calcium asis, likewise, this same alloy when it also contains about 0.05 to 0.4per cent of one or more of the class of elements composed of antimonyand bismuth. Another excellent aluminum base alloy prepared inaccordance with the principles of my invention is one containing 3.0 to8.0 per cent of magnesium, 0.5 to 4.0 per cent of nickel, 0.5 to 4.0 percent of manganese, and 0.05 to 2.0 per cent of calcium, which alloy mayalso be improved, particularly for application at high temperatures, bythe addition of 0.05 to 0.4 per cent of at least one of the class ofelements composed of antimony and bismuth.

The principles of my invention find particular application in the caseof aluminum base alloys containing magnesium, nickel, and chromium, andaluminum base alloys containing magnesium, nickel, and copper, as wellas those alloys containing magnesium, nickel, and cobalt.

' Examples may begiven of aluminum base alloys containing 2.0 to 10.0per cent of magnesium, 0.2 to 5.0 per cent of nickel, 0.5 to 3.5 percent of chromium, and 0.05 to 2.0 per cent of calcium. An aluminum basealloy containing 3.0 to 8.0 per cent of magnesium, 0.5 to 3.5 per centof nickel, 0.5 to 3.5 per cent of chromium, and 0.05 to 2.0 per cent ofcalcium has excellent casting properties and the high temperatureproperties of this alloy can be favorably affected by the addition of0.05' to 0.4 per cent of at least one of a class of elements composed ofbismuth and antimony. Examples may be given of aluminum base alloycontaining 2.0 to 10.0 per cent of magnesium, 0.2 to 5.0 per cent ofnickel, 1.0 to 6.0 per cent of copper, and 0.05 to 2.0 per cent ofcalcium. An excellent alloy of this type is one containing 3.0 to 8.0per cent of magnesium, 0.5 to 5.0 per cent of nickel, 1.0 to 6.0 percent of copper, and 0.05 to 2.0 per cent of calcium with or without 0.05to 0.4 per cent of at least one of the class of elements composed ofantimony and bismuth and with or without the further addition of 0.5 to3.5 per cent of at least one of a class of elements composed of cobaltand chromium, and with or without the further addition of 0.1 to 1.0 percent of at.

least one of a class of elements composed of tungsten, vanadium,molybdenum, titanium, and zirconium.

Other excellent alloys are those aluminum base alloys containing about2.0 to 10.0 per cent magnesium, 0.2 to 5.0 per cent nickel, 0.1 to 3.5per cent cobalt, and 0.05 to 2.0 per cent 01 calcium. A particularexample of this class of alloys, which may also contain withconsiderable advantage 0.05 to 0.4 per cent of a class of elementscomposed of antimony and bismuth, is the aluminum base alloy containing3.0 to 8.0 per cent magnesium, 0.5 to 4.0 per cent nickel, 0.1 to 3.0per cent cobalt, and 0.05 to 2.0 per cent calcium. a

Among other magnesium-containing aluminum cent of copper, 0.5 to 3.5 percent of chromium, F."

and 0.05 to 2.0 per cent of calcium, with or without the addition of0.05 to 0.4 per cent of at least one of a class of metals composed ofantimony and bismuth and with or without the addition of other alloyingelements.

The alloys herein described may be produced u by the usual methods ofalloying metals. calciumis preferably added to the molten alloy bythrusting the calcium beneath the surface with tongs or other suitableinstrument. The 7.

aluminum used in preparing the alloys may be pure or it may contain theimpurities found in commercial grades of this metal. Ordinarily a goodcommercial grade of virgin aluminum will give excellent results and ispreferable.

Having thus explained and described my invention, I claim: I, A metallicalloy consisting of 3.0 to 8.0 per cent by weight of magnesium, 0.5 to5.0 per cent by weight of nickel, 1.0 to 6.0 per cent by weight I.

of copper, 0.1 to 1.0 per cent by weight of at least one of a class ofelements composed of-

